1. Field of the Invention
The present invention relates to an electric motor having a labyrinth structure.
2. Description of the Related Art
In some electric motors (or rotating electrical machines) having a stator and a rotor, a structure for preventing water or foreign material entering a clean area or the inside of the motor may be arranged. As a relevant prior art document, JP 2015-223022 A discloses an electric motor having an air-purging function. Concretely, this document describes that the electric motor has an air supply port for supplying pressurized air, and an air flow channel, which extends straight from the air supply port to a space around a bearing, and is communicated with a space for containing a winding wire.
JP H09-322465 A discloses an air guide/discharge unit including a fixed axis having a horizontal hole and a vertical hole so that air can enter the horizontal hole and flow out from the vertical hole, by which particles of lubricant or foreign material can be prevented from diffusing into a clean area.
Further, JP 2005-192363 A discloses an outer-rotor type motor including a hosing having a vent hole formed on an inner surface of the housing, in which foreign particles may be blown toward an outer peripheral of the motor due to a dynamic pressure in a groove of housing and a centrifugal force generated by the rotation of a rotor.
On the other hand, JP 2010-022115 A discloses an electric motor including a labyrinth section having a serpentine path, by which water can be prevented from entering an inside of the motor.
When the air-purging structure as described in JP 2015-223022 A is used, it is necessary to prepare a device or power for operating the structure, and thus the cost of the system including the structure may be increased. Further, a sealing function of the conventional labyrinth is often insufficient.